Re: x86/AMD: Nested hvm crashes in 4.3

[Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>]

On 6/27/2013 5:08 AM, Jan Beulich wrote:
>>>> On 27.06.13 at 11:20, Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> wrote:
>> On 6/27/2013 3:22 AM, Jan Beulich wrote:
>>>>>> On 27.06.13 at 02:24, Suravee Suthikulanit <suravee.suthikulpanit@amd.com> wrote:
>>>> I have found an issue in where the system crash right when I start
>>>> another HVM guest inside an HVM guest.  I have traced back to the patch
>>>> which the issue started.
>>>>
>>>> commit f1bde87fc08ce8c818a1640a8fe4765d48923091
>>>> Author: Jan Beulich <jbeulich@suse.com>
>>>> Date:   Fri Feb 8 11:06:04 2013 +0100
>>>>
>>>>        x86: debugging code for testing 16Tb support on smaller memory systems
>>>>
>>>>        Signed-off-by: Jan Beulich <jbeulich@suse.com>
>>>>        Acked-by: Keir Fraser <keir@xen.org>
>>> We had issues exposed by this patch before, but any such issue
>>> would just have been masked before that patch (and would
>>> surface on a system with more than 5Tb of memory anyway).
>> The system I am having the issue has 48GB of memory.
> Which is why you're seeing the problem only with the debugging
> code enabled.
Is the "debugging" enabled by default?  I didn't specify any debug when 
building.
How can I check and disable debugging?

> (And of course I didn't really expect you to have
> tried this on a huge memory system - they're just too rare still
> for this to be likely.)
>
>>> So it is very unlikely for the patch itself to be at fault.
>> I have traced the issue and found that the system crashing starts from this
>> commit id and onward.
>> (i.e. The system does not crash with commit id
>> ed759d20249197cf87b338ff0ed328052ca3b8e7)
>> So, I am still believe that this patch has somehow triggered the issue.
> As said - I'm pretty certain this merely unmasked an already
> lurking issue.
I'm not quite sure what you meant here.  Are you saying that this 
"crashing" is a known issue?

>   And that's what the purpose of that patch is.
This patch is crashing the system. What do you mean by "And that's what 
the purpose of that patch is"?

Suravee
>
> Jan
>
>